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LOGO HEREAn Overview of EMC ChambersDonald J GrayPhotoGoesHereDirector of Business Development
Review of EMC TestingElectromagnetic Compatibility (EMC) TestingRadiatedConductedTest: How much energy isemitted by the EUT?EmissionEmissionTest: Can your devicewithstand externalenergy?ImmunityImmunity
Shield Rooms Conducted EMIConducted EMSIncludes Transients (e.g., ESD, Surge, Burst)Control Rooms & Amplifier Rooms
Radiated TestingElectromagnetic Compatibility (EMC) TestingRadiatedConductedTest: How much energy isemitted by the EUT?EmissionEmissionTest: Can your devicewithstand externalenergy?ImmunityImmunity
Why Do We Use A Chamber? Early Testing Done Outdoors– Open-Air Test Sites (OATS) – EMC– Outdoor Far-field Ranges – Antenna Measurements But Issues Exist Outdoors Noisy Environment– Ambient Signals– Reflections from Nearby Structures Creating Unauthorized Signals! Protection from Weather Security
EMC Anechoic Chamber Types 3m CAC3m Chamber5m Chamber10 m ChamberMIL-STD-461CISPR 25ISO 11452-2ETSICISPR 12All Refer to Commercial Testing –CISPR 16, FCC, Etc Compliance vs Precompliance Partially lined Semi-anechoic (conductivefloor) Fully-anechoic Turntables & TowersMost common chambers are thecompact and full-compliance 3mchambers
OATS vs. ChamberLiberty Labs, Kimballton, Iowa
EMI Testing - Data Collection Full Cylinder of Data– Antenna Height: 1- 4 m– 3600 Antenna Tower Turntable
Semi-Anechoic Chamber Absorber on FiveSides Shielded Minimize Reflections Ground Plane Reflection Like OATS Correlation
Performance of a Chamber Decreases the Reflections – Unwanted SignalsAllows Measurement of Wanted SignalCreates a Quiet Zone for Optimum TestingThis Creates Better “Performance”
What is a Quiet Zone? A Volume of Space (typically a cylinder) in Which theleast amount of disturbance from “unwanted” signalsis r-relationship between: Size of QZ Size of Chamber Size of Absorber
Carbon-Loaded, Polyurethane MaterialPyramidal/Wedge-Shaped Absorber Carbon Loaded Tapered Shape Creates Tapered Resistances Creates Transition of Many Tiny Reflections asEM Wave Passes through Absorber These Tend to Cancel Each Other Out Common Rule of Thumb (EMC): Length Shouldbe Half-Wavelength of Lowest Frequency
Ferrite TilesFerrite Tiles100 x 100 mm 5.2 – 6.7 mm thick
How Does Absorber Work?Hybrid Absorber Combines the Magnetic & Resistive Losses Must Create Effective Impedance Match If Not, Greater Reflections CreatedFerrite TileShielding377 ΩEM WaveGradual Increase inResistanceBase
Compact 3 m Chambers (CAC) EMC-MC Mini Compact Chamber– 6m x 3m x 2.4m– QZ 0.5 m to 1.0 m (?)– Performance Below 300 MHz Not Good( 6.0 dB below; 4.0 dB above)– Cannot Fit Antenna Tower! EMC-3C Compact Chamber– 7m x 3m x 3m– QZ up to 1.5 m– Performance Below 300 MHz is Not Good ( 6.0 dB below; 4.0dB above)– Use a Reduced Height Ant Tower (2.4 m) Still Maintain 3m Test Distance (EMI & EMS)
Full Compliance 3 m Chamber Dimensions: 8.9 m x 5.6 m x 5.8 m QZ Up to 2.0 Excellent Performance – Entire Frequency Range
Dimensions for 3m SAC Test Distance to AntennaTest Volume SizeAntenna FootprintAbsorber Size (each wall)Clearance to AbsorberTotal Length 3m1.5m1.5m1m (0.5m x 2)2m (1m x 2)9m This is 3x the required test distance!
5 m Chamber Actually Oversized 3 m chambers!!! Dimensions: 11.5 m x 7.5 m x 5.8 m QZ 2 to 4 m (can handle larger EUTs!!)– NSA Compliance tested to 3 m ONLY!!!– SVSWR Compliance tested to 3 m ONLY!!!! Excellent Performance – Entire Frequency Range Longer & Much Wider (can fit “dual masts”) Larger Personnel Door (3.0 m x 3.0 m vs 0.9 m x 2.1 m) Chamber validated at a 3m distance Can do EMI testing at 5 m - More easily correlated to the 10 m distance
10 m Chamber Dimensions: 21 m x 12 m x 8.5 m QZ 4 m (can handle larger EUTs!!)– NSA Compliance tested to 10 m– SVSWR Compliance tested to 3 m ONLY!!!! Excellent Performance – Entire Frequency RangeTwice as Long as 5 m and wider/higherLarger Personnel Door (3.0 m x 3.0 m vs 0.9 m x 2.1 m)Very Large EUTs; Full Automotive TestingGenerally Considered the “Gold Standard”
Radiated Emissions Testing 1 GHz SVSWR Method of Verification Absorber 30 cm (assuming EUT/TT flush with theFloor)
IEC 61000-4-3 Radiated Immunity Testing Compliant 3m Radiated Immunity Add Ferrite Tiles Plus Absorber Achieve Field Uniformity
MIL-STD-461/RTCA DO 160RTCA DO 160MIL-STD-461(1)(2)Reference MIL-STD-461F, 10 December 2007(1)(1)(2)Reference RTCA DO 160F, December 6, 2007Reference MIL-STD-461F, 10 December 2007(2)
MIL-STD-461/RTCA DO 160RTCA DO 160MIL-STD-461(1)Reference RTCA DO 160F, December 6, 2007 Reference MIL-STD-461F, 10 December 2007Can Easily Uses Truncated 24” AbsorberOr. Can Use Shorter Hybrid MaterialBoth Meet: DO 160 and MIL-STD specsChamber Size Usually Small – but depends on EUT size.(1)(2)(2)Reference RTCA DO 160F, December 6, 2007Reference MIL-STD-461F, 10 December 2007
MIL-STD RequirementsExample Chamber Config for MIL-STD-461
CISPR 25 Requirements(1)(1) Requirement is for absorbercoverage on walls/ceiling Performance is based purelyon absorber reflectivity Can be smaller chambers Difficult at lower frequenciesor for Immunity testingReference CISPR25:2008(1) Reference CISPR25:2008
Chamber Performance(1) Don’t need hybrid if absorber is about 1 m long Typical hybrid absorber with 30 cm absorber will work(1) Reference CISPR25:2008
CISPR 25 Requirements(1)(1)(1)(1)Reference CISPR25:2008(1) Reference CISPR25:2008
ISO 11452-2 Very Similar to CISPR25 ChamberFull Absorber on Walls/CeilingOften Combined w/ CISPR25Bigger Antennas to Handle Higher Power – AffectsChamber Size Dimensions – Depend on:– Absorber Size– EUT & Test Bench Size– Antenna Dimensions(1) Reference ISO 11452-2:2004(1)(1)
Chamber Performance(1) Don’t need hybrid if absorber is about 1 m long Typical 30 cm, hybrid material will work(1) Reference ISO 11452-2:2004
ISO 11452-2 – Antenna Selection(1)(1)Reference ISO 11452-2:2004Reference ISO 11452-2:2004(1) Reference ISO 11452-2:2004
Fully Anechoic Rooms (FARs) Alternative to SAC CISPR16 (FSNSA) ETSI Standards Performance Specs:Similar to CISPR25(Specs Reflectivity of Absorber)ETSI (FAR) Absorber Performance Requirements 10dB 30-100MHz 20dB 100-300MHz 30dB 300MHz-10GHz
Full Vehicle Testing Testing at 10 m Distances Chamber Sizes are Customized Need to Accommodate Full Vehicles– Dynomometers– Specialized Facilities– Specialized, Extremely Large Antennas– Much Higher Power
Turntable & Dynomometer Considerations Budget Flexibility FeaturesLarge TT, No DynoExtremely Large TT, No DynoCourtesy of MaturoPortable Dyno, on top of TTCourtesy of MaturoPortable Dyno, no TTCourtesy of MaturoBuilt-in Dyno, no TTTT with integrated DynoCourtesy of Maturo
Specialized Facility Considerations Large Doors & TT’sFire SuppressonHVACHoistsIncreased CostsHigh Capacity TurntablesAutomatic and SemiAutomatic Doors &RampsFire SuppressionHVAC SystemsLift Mechanisms
Large Chambers & Customized ShapesLarge Dual-Purpose ChambersCustomized “Domed” ShapesCustomized Absorber Topologies: Varying shapes Varying Heights and directions “Baffled” AbsorbersTapered ChambersExtremely Large Rectangular Chambers
Thanks for attending!Mark your calendars for EMC LIVE 2016April 26-28, 2016
MIL-STD-461/RTCA DO 160 Reference RTCA DO 160F, December 6, 2007 Reference MIL-STD-461F, 10 December 2007 (1) (2) (1) Reference RTCA DO 160F, December 6, 2007 (2) Reference MIL-STD-461F, 10 December 2007 . Example Chamber Config for MIL-STD-461 MIL-STD Requirements. CISPR 25 Requirements Requirement is for absorber coverage on walls/ceiling Performance is based
